<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Function template public_function</title>
<link rel="stylesheet" href="../../../../../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="../../index.html" title="Chapter 1. Boost.Contract 1.0.0">
<link rel="up" href="../../reference.html#header.boost.contract.public_function_hpp" title="Header &lt;boost/contract/public_function.hpp&gt;">
<link rel="prev" href="public_f_idm45125847762768.html" title="Function template public_function">
<link rel="next" href="public_f_idm45125847708832.html" title="Function template public_function">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../boost.png"></td>
<td align="center"><a href="../../../../../../index.html">Home</a></td>
<td align="center"><a href="../../../../../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../../../../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="public_f_idm45125847762768.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../reference.html#header.boost.contract.public_function_hpp"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="public_f_idm45125847708832.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="refentry">
<a name="boost.contract.public_f_idm45125847738960"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2><span class="refentrytitle">Function template public_function</span></h2>
<p>boost::contract::public_function — Program contracts for void public functions overrides (virtual or not). </p>
</div>
<h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2>
<div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: &lt;<a class="link" href="../../reference.html#header.boost.contract.public_function_hpp" title="Header &lt;boost/contract/public_function.hpp&gt;">boost/contract/public_function.hpp</a>&gt;

</span>
<span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> Override<span class="special">,</span> <span class="keyword">typename</span> F<span class="special">,</span> <span class="keyword">typename</span> Class<span class="special">,</span> <span class="keyword">typename</span><span class="special">...</span> Args<span class="special">&gt;</span> 
  <a class="link" href="specify__idm45125848100512.html" title="Class template specify_precondition_old_postcondition_except">specify_precondition_old_postcondition_except</a> 
  <span class="identifier">public_function</span><span class="special">(</span><a class="link" href="virtual_.html" title="Class virtual_">virtual_</a> <span class="special">*</span> v<span class="special">,</span> <span class="identifier">F</span> f<span class="special">,</span> <span class="identifier">Class</span> <span class="special">*</span> obj<span class="special">,</span> <span class="identifier">Args</span> <span class="special">&amp;</span><span class="special">...</span> args<span class="special">)</span><span class="special">;</span></pre></div>
<div class="refsect1">
<a name="idm45885983301264"></a><h2>Description</h2>
<p>This is used to specify preconditions, postconditions, exception guarantees, old value copies at body, and check class invariants for public function overrides (virtual or not) that return <code class="computeroutput">void:</code> </p>
<pre class="programlisting"><span class="keyword">class</span> <span class="identifier">u</span>
    <span class="preprocessor">#define</span> <span class="identifier">BASES</span> <span class="keyword">private</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">constructor_precondition</span><span class="special">&lt;</span><span class="identifier">u</span><span class="special">&gt;</span><span class="special">,</span> \
            <span class="keyword">public</span> <span class="identifier">b</span><span class="special">,</span> <span class="keyword">private</span> <span class="identifier">w</span>
    <span class="special">:</span> <span class="identifier">BASES</span>
<span class="special">{</span>
    <span class="keyword">friend</span> <span class="keyword">class</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">access</span><span class="special">;</span>

    <span class="keyword">typedef</span> <span class="identifier">BOOST_CONTRACT_BASE_TYPES</span><span class="special">(</span><span class="identifier">BASES</span><span class="special">)</span> <span class="identifier">base_types</span><span class="special">;</span>
    <span class="preprocessor">#undef</span> <span class="identifier">BASES</span>

    <span class="keyword">void</span> <span class="identifier">invariant</span><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span> <span class="special">{</span> <span class="comment">// Optional (as for static and volatile).</span>
        <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
        <span class="special">...</span>
    <span class="special">}</span>

    <span class="identifier">BOOST_CONTRACT_OVERRIDES</span><span class="special">(</span><span class="identifier">f</span><span class="special">)</span>

<span class="keyword">public</span><span class="special">:</span>
    <span class="comment">// Override from `b::f`.</span>
    <span class="keyword">void</span> <span class="identifier">f</span><span class="special">(</span><span class="identifier">t_1</span> <span class="identifier">a_1</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">t_n</span> <span class="identifier">a_n</span><span class="special">,</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">virtual_</span><span class="special">*</span> <span class="identifier">v</span> <span class="special">=</span> <span class="number">0</span><span class="special">)</span> <span class="special">{</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">old_ptr</span><span class="special">&lt;</span><span class="identifier">old_type</span><span class="special">&gt;</span> <span class="identifier">old_var</span><span class="special">;</span>
        <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">check</span> <span class="identifier">c</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">contract</span><span class="special">::</span><span class="identifier">public_function</span><span class="special">&lt;</span>
                <span class="identifier">override_f</span><span class="special">&gt;</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="special">&amp;</span><span class="identifier">u</span><span class="special">::</span><span class="identifier">f</span><span class="special">,</span> <span class="keyword">this</span><span class="special">,</span> <span class="identifier">a_1</span><span class="special">,</span> <span class="special">...</span><span class="special">,</span> <span class="identifier">a_n</span><span class="special">)</span>
            <span class="special">.</span><span class="identifier">precondition</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
                <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
                <span class="special">...</span>
            <span class="special">}</span><span class="special">)</span>
            <span class="special">.</span><span class="identifier">old</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
                <span class="identifier">old_var</span> <span class="special">=</span> <span class="identifier">BOOST_CONTRACT_OLDOF</span><span class="special">(</span><span class="identifier">v</span><span class="special">,</span> <span class="identifier">old_expr</span><span class="special">)</span><span class="special">;</span>
                <span class="special">...</span>
            <span class="special">}</span><span class="special">)</span>
            <span class="special">.</span><span class="identifier">postcondition</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
                <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
                <span class="special">...</span>
            <span class="special">}</span><span class="special">)</span>
            <span class="special">.</span><span class="identifier">except</span><span class="special">(</span><span class="special">[</span><span class="special">&amp;</span><span class="special">]</span> <span class="special">{</span> <span class="comment">// Optional.</span>
                <span class="identifier">BOOST_CONTRACT_ASSERT</span><span class="special">(</span><span class="special">...</span><span class="special">)</span><span class="special">;</span>
                <span class="special">...</span>
            <span class="special">}</span><span class="special">)</span>
        <span class="special">;</span>

        <span class="special">...</span> <span class="comment">// Function body.</span>
    <span class="special">}</span>
    
    <span class="special">...</span>
<span class="special">}</span><span class="special">;</span>
</pre>
<p>A public function override should always call  <code class="computeroutput"><code class="computeroutput"><a class="link" href="public_f_idm45125847806592.html" title="Function template public_function">boost::contract::public_function</a></code></code> otherwise this library will not be able to correctly use it for subcontracting.</p>
<p><span class="bold"><strong>See Also:</strong></span></p>
<p> <a class="link" href="../../boost_contract/tutorial.html#boost_contract.tutorial.public_function_overrides__subcontracting_" title="Public Function Overrides (Subcontracting)">
        Public Function Overrides</a></p>
<p>
</p>
<p>



</p>
<div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term">Parameters:</span></p></td>
<td><div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><code class="computeroutput">args</code></span></p></td>
<td><p>All arguments passed to the enclosing public function override declaring the contract (by reference and in the order they appear in the enclosing function declaration), but excluding the trailing argument <code class="computeroutput">v</code>.</p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">f</code></span></p></td>
<td><p>A pointer to the enclosing public function override declaring the contract (but see <a class="link" href="../../boost_contract/advanced.html#boost_contract.advanced.function_overloads" title="Function Overloads">
            Function Overloads</a>). </p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">obj</code></span></p></td>
<td><p>The object <code class="computeroutput">this</code> from the scope of the enclosing public function override declaring the contract. This object might be mutable, <code class="computeroutput">const</code>, <code class="computeroutput">volatile</code>, or <code class="computeroutput">const volatile</code> depending on the cv-qualifier of the enclosing function (volatile public functions will check volatile class invariants, see  <a class="link" href="../../boost_contract/extras.html#boost_contract.extras.volatile_public_functions" title="Volatile Public Functions">
            Volatile Public Functions</a>). </p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">v</code></span></p></td>
<td><p>The trailing parameter of type  <code class="computeroutput"><code class="computeroutput"><a class="link" href="virtual_.html" title="Class virtual_">boost::contract::virtual_</a></code></code><code class="computeroutput">*</code> and default value <code class="computeroutput">0</code> from the enclosing public function override. </p></td>
</tr>
</tbody>
</table></div></td>
</tr>
<tr>
<td><p><span class="term">Template Parameters:</span></p></td>
<td><div class="variablelist"><table border="0" class="variablelist compact">
<colgroup>
<col align="left" valign="top">
<col>
</colgroup>
<tbody>
<tr>
<td><p><span class="term"><code class="computeroutput">Args</code></span></p></td>
<td><p>The types of all parameters passed to the enclosing public function override declaring the contract, but excluding the trailing parameter type <code class="computeroutput"><code class="computeroutput"><a class="link" href="virtual_.html" title="Class virtual_">boost::contract::virtual_</a></code>*</code>. On compilers that do not support variadic templates, this library internally implements this function using preprocessor meta-programming (in this case, the maximum number of supported arguments is defined by  <code class="computeroutput"><code class="computeroutput"><a class="link" href="../../BOOST_CONTRACT_MAX_ARGS.html" title="Macro BOOST_CONTRACT_MAX_ARGS">BOOST_CONTRACT_MAX_ARGS</a></code></code>). (Usually these template parameters are automatically deduced by C++ and they do not need to be explicitly specified by programmers.)</p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">Class</code></span></p></td>
<td><p>The type of the class containing the virtual public function declaring the contract. (Usually this template parameter is automatically deduced by C++ and it does not need to be explicitly specified by programmers.) </p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">F</code></span></p></td>
<td><p>The function pointer type of the enclosing public function override declaring the contract. (Usually this template parameter is automatically deduced by C++ and it does not need to be explicitly specified by programmers.) </p></td>
</tr>
<tr>
<td><p><span class="term"><code class="computeroutput">Override</code></span></p></td>
<td><p>The type trait <code class="computeroutput">override_<span class="emphasis"><em>function-name</em></span></code> declared using the <code class="computeroutput"><code class="computeroutput"><a class="link" href="../../BOOST_CONTRACT_OVERRIDE.html" title="Macro BOOST_CONTRACT_OVERRIDE">BOOST_CONTRACT_OVERRIDE</a></code></code> or related macros. This template parameter must be explicitly specified (because there is no function argument from which it can be automatically deduced by C++). </p></td>
</tr>
</tbody>
</table></div></td>
</tr>
<tr>
<td><p><span class="term">Returns:</span></p></td>
<td><p>The result of this function must be assigned to a variable of type  <code class="computeroutput"><a class="link" href="check.html" title="Class check">boost::contract::check</a></code> declared explicitly (i.e., without using C++11 <code class="computeroutput">auto</code> declarations) and locally just before the code of the public function body (otherwise this library will generate a run-time error, see  <code class="computeroutput"><a class="link" href="../../BOOST_CO_idm45125848615536.html" title="Macro BOOST_CONTRACT_ON_MISSING_CHECK_DECL">BOOST_CONTRACT_ON_MISSING_CHECK_DECL</a></code>). </p></td>
</tr>
</tbody>
</table></div>
</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2008-2019 Lorenzo Caminiti<p>
        Distributed under the Boost Software License, Version 1.0 (see accompanying
        file LICENSE_1_0.txt or a copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
      </p>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="public_f_idm45125847762768.html"><img src="../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../reference.html#header.boost.contract.public_function_hpp"><img src="../../../../../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="../../index.html"><img src="../../../../../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="public_f_idm45125847708832.html"><img src="../../../../../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
